三峡水库运用后长江中游河床冲淤调整特征流量变化对比研究

Comparative Study on the Variations in Characteristic Discharges for Channel Morphological Adjustments at the Middle Yangtze River after the Impoundment of the Three Gorges Reservoir

摘要: 为对比分析三峡水库下游河床冲淤调整特征流量时空变化规律，选取1981~2016年长江中游宜昌、枝城、沙市、监利、螺山和汉口6个主要水文站实测资料计算造床流量、有效流量和平滩流量，并分析特征流量变化的统计特性。结果表明，三峡水库蓄水运用后，不同特征流量发生了差异性调整，造床流量呈一致减小的变化趋势，有效流量与平滩流量的变化呈明显的空间分异性；与之相应，不同特征流量在累计水沙输移占比、流量频率以及流量重现期等方面的变化有所不同。蓄水前后，各水文站造床流量累计流量频率变化均较小，有效流量累计径流占比、累计输沙占比和累计流量频率在蓄水后一致增加，平滩流量与1.5年重现期流量大致相当。

Abstract: To explore and compare the temporal-spatial variation rules of characteristic discharges for channel morphological adjustments downstream of the Three Gorges Reservoir (TGR), the field data of six main hydrometric stations at the Middle Yangtze River, i.e., Yichang, Zhicheng, Shashi, Jianli, Luoshan and Hankou, were used for the calculation of dominant discharge, effective discharge and bank-full discharge and analysis of their statistic characteristics. The results show that after the impoundment of TGR, different characteristic discharges changed differently: The dominant discharges within the studied reaches showed a consistent decreasing trend, while the effective discharge and bank-full discharge variations behaved an obviously spatial differentiation. Accordingly, the changes of accumulative flow runoff percentage, accumulative sediment runoff percentage, flow frequency and flow recurrence period for different characteristic discharges were also different: After the impoundment of TGR, the accumulative flow frequency for dominant discharge at each hydrometric station changed very slightly, while the accumulative flow runoff percentage, accumulative sediment runoff percentage and accumulative flow frequency for effective discharge increased consistently, and the bank-full discharge at each hydrometric station was roughly equivalent to the corresponding 1.5-year recurrence period discharge.